3. Servicing
Cycle components
SMGB0082 rev.1 - 07/2015
85
3
3.5.2 Overhaul work
Perform the work according to “Semi-hermetic Hitachi Screw Compressor Manual”.
When removing a compressor from the refrigeration cycle, high pressure part shall be separated between the projecting
part flange of compressor and the upper cover of oil separator. Do not separate high pressure part between the check valve
and the projecting part flange of compressor, as collected refrigerant would be spilled out.
Low-pressure side
Disconnect from this part
High-pressure side
Disconnect from this part
Upper cover of
oil separator
Projecting part flange
of compressor
Check valve
Do not remove these bolts or
refrigerant is ejected
Remove these
bolts firstly
Replacement of oil inside compressor
To replace the oil of the compressor proceed as explained below:
1
Collect all refrigerant into a condenser before this work. Recover the rest of refrigerant from the water cooler and the
compressor.
2
With a module capacity of 50~75%, perform the operation ensured by suction gas superheat for about 10 minutes, and
after recovering the refrigerant as explained in
Recovery of refrigerant
in the Installation and Operation manual, turn
power off and perform the following operation.
3
Oil extraction work
Remove the plugs for oil extraction (A-B) at 2 places in screw compressor, and measure the amount of extracted oil. It
is not possible to extract the oil from the inside of compressor by just removing one plug, so always remove the 2 plugs.
4
Check of oil strainer
Remove the oil strainer cover (C), and confirm the state of the internal oil strainer. In case of finding any abnormality
such as dirt or any damage, clean or replace the part as adequate.
5
Oil charge work
Attach the oil strainer, the oil strainer cover (C) and the oil extraction plugs (A-B). Connect the charge hose to the check
joint (Discharge pressure outlet). Let the oil be absorbed by the charge hose while performing vacuum from the check
joint of the suction side. (Charge the amount of oil that had been extracted in the above point “Oil extraction work”)
6
After completing the operation, perform vacuum again and charge refrigerant (check in the Installation and Operation
Manual,
Maintenance
chapter).
N O T E
• Use a clean charge hose.
In order to avoid absorption of atmospheric moisture by refrigerant oil, use a container with a small opening and complete
the operation in the shortest time possible (within 20 minutes as a criterion).
